The present invention relates to a computer aided design system for use in synthetic resin moldings design and mold design, and a three-dimensional design method using the same, and a storing medium.
In recent years, according to demands for more variety of product design, users"" various usages etc., plastics have been widely used as material of enclosures for electrical products since they may present an attractive appearance and may be molded arbitrarily. In addition, it entails such advantages that reduction in the number of parts and simplification of assembly may be attained. This is because seats, bosses (projections), etc., these being used for mounting printed circuit boards and other parts, and reinforcing members such as ribs may be formed integrally with the enclosures if the enclosures are fabricated by resin injection molding.
FIG. 1A shows an example of moldings (molded products) formed by resin injection molding. In FIG. 1A, a reference 1 denotes a molding used as an enclosure of a portable electronic device, and a reference 2 denotes a bore portion provided in the molding 1. After preparing the mold in which a cavity having the same profile as that of the product is in advance formed, melted resin is filled into the cavity and then cured, so that the molding 1 with a shape shown in FIG. 1A may be formed. At this time, the bore portion 2 may be formed by nests arranged in the mold.
FIG. 1B shows a configuration of the mold. In FIG. 1B, a reference 3 denotes a cavity (female mold) for defining an outer shape of the molding 1, and a reference 4 denotes a core (male mold) for defining an inner shape of the molding 1. When the cavity 3 is put on the core 4, the cavity corresponding to the products profile to be formed may be formed between them.
FIG. 1C shows a configuration of an injection molding machine on which the mold is mounted. With being arranged so as to oppose to each other in the vertical direction, the cavity 3 and the core 4 are clamped on a cavity plate 3A and a core plate 4A respectively. The cavity plate 3A may be driven by a driving apparatus (not shown) to move in the vertical direction. A reference 5 denotes a runner stripper plate in which a runner (not shown) is formed to introduce the resin 7 into the space in the mold. The runner stripper plate 5 may be placed on the cavity plate 3A. When the molds are opened, the runner stripper plate 5 may then be separated from the cavity plate 3A to enable the resin cured in the runner to be removed from the runner. A reference 6 denotes a gate (pouring gate) formed in the mold. Resin 7 is filled into the cavity in the mold via the gate 6.
A reference 8 denotes a gas vent (breathing hole) which is provided in the mold to exhaust the air from the space in the mold to the exterior when the resin is poured into the space in the mold. A reference 9 denotes a cooling water path provided in the mold. Since the resin to be filled into the mold is heated at a temperature of a few hundreds xc2x0 C., a temperature of the mold is raised when the resin is filled into the mold. As a result, drawbacks such as not only reduction in molding efficiency but also warpage, twist, etc. of the product are caused. In order to prevent the drawbacks, the mold is cooled by flowing water through the cooling water path 9. Usually, the cooling water path 9 is provided on the core 4 side.
A reference 10 denotes an extruder portion for extruding the moldings 1 from the core 4. The extruder portion 10 has a rod-like member referred to as an ejector pin. The moldings 1 can be extruded from the core 4 by inserting the ejector pin into a through hole provided in the core 4.
In any event, since the injection mold is composed of the cavity 3 and the core 4, as mentioned above, the mold must be split into the cavity 3 side and the core 4 side when designing the mold. The split plane is called a parting plane. In case there is caused an undercut portion in the products to be fabricated, the moldings cannot be stripped off from the mold if the parting plane is set incorrectly. Here the undercut portion may be defined as a portion serving as an engagement formed in the mold opening direction when the product is taken out from the molds. If the undercut portion exists, consideration for providing a slide structure to the mold or the like should be taken inevitably.
In order to strip the product off from the mold readily, slight slopes (draft slopes) are provided on the surface of the mold so as to prevent inner surfaces of the mold from being formed perpendicularly to the parting plane. In the prior art, in the case of the mold having a relatively simple profile, mold designers be able to design the mold according to drawings prepared for the product while considering parting plane, draft slope, etc. Conversely, as for the product which must be designed by means of a plenty of free-form surfaces to achieve the high design property, it would become difficult to illustrate the profile of the product in the drawings. As a countermeasure to this drawback, first the product model (model) is formed, then profile lines of the product model are illustrated with many dots, and then the profile of the product is converted into numeric data by correlating these dots with each other in terms of digitizing process. Then NC (Numeric Control) data used for cutting process and electric discharge machining electrodes are then prepared for based on the numeric data. According to these data, the mold may be then fabricated by the electric discharge machining electrodes.
In the meanwhile, there are some cases where the mold may be designed by means of the three dimensional CAD (Computer-Aided Design) system. In such cases, data of the product shape are first input into the CAD system, then the product shape or the mold block (i.e., virtual block displayed on the screen for illustrating an outer shape of the mold) in which a cavity corresponding to the product shape is formed is depicted on the display. While monitoring the screen of the display, the designer may draw the parting line on the screen to form the, parting plane or select the planes to which a draft slope is provided. The CAD system may thus output numeric data to form the mold in compliance with these setting conditions.
However, in the method where the designer has to design the mold on the basis of the design drawings, the designer must design the mold while considering undercut, draft slope, etc. as mentioned above. Therefore, it can be seen that, in the case of the product with complicate profile, it would become difficult for the designer to determine a solid product shape from the drawings. For this reason, according to this method, problems have been arisen that man-hour in design is increased and design error is prone to generate. Alternatively, in the method where data used for fabricating the mold are generated from the product model, there are some problems that, since the product model must be formed to have a precise profile, the designer must be well practiced in forming the product model and much time must also be consumed to form the product model.
Moreover, in the method where the three dimensional CAD system is used, the troublesome procedures would be required and further a great deal of skill would be required for the designer since the mold designer must design parting plane, draft slopes, etc. on the basis of image displayed on the screen of the display. Because of the causes such as missing of the undercut portion, the mold designer is apt to generate errors in design.
For the synthetic resin moldings such as a plastic case for an electronic device, the shorter time limit of delivery is requested according to frequent occurrence of the model change in addition to diversification of design and complication of shape. Therefore, the moldings design must be carried out more smoothly by grasping the design contents more easily and more quickly and also the mold design must be carried out more smoothly in molding makers.
Hence, a method has been proposed wherein the synthetic resin molding products can be three-dimensionally designed by use of the computer aided design system such that the design object can be monitored at any angle and tolerances are added to its shape data (see literature 1: Patent Application Publication (KOKAI) Hei 6-342,458).
Further, another method has been proposed wherein candidates of split planes of the split mold can be found automatically by use of three-dimensional data to suggest them to a mold designer and also split planes can be decided automatically to suggest their three-dimensional images to the mold designer (see literature 2: Patent Application Publication (KOKAI) Hei 7-334,555 and literature 3: Patent Application Publication (KOKAI) Hei 9-185,647).
Further, the molding shrinkage rate which is a rate of deviation in dimension of the moldings to mold dimensions has become different based on type of the synthetic resin as molding material, shape and thickness of the moldings, and molding conditions such as temperature, pressure, etc. Such difference in the molding shrinkage rate has caused an obstacle to the above shorter time limit of delivery. Still another method has been proposed wherein an amount of deformation can be calculated according to simulation in order to overcome such cause (see literature 4: Patent Application Publication (KOKAI) Hei 6-55,597).
However, according to the method set forth in the literature 1, the method is insufficient for the attribute information added to the three-dimensional shape to shorten the time limit of delivery of the moldings since such method simply adds only the tolerance to the three-dimensional shape.
Further, according to the methods set forth in the literatures 2 and 3, in some cases, flash and sink which are formed in portions corresponding to parting planes (parting lines) of the mold would be formed in undesired positions since transfer of inhibit information of such flash and sink is delayed.
Furthermore, according to the method set forth in the literature 4, such simulation has no relevance to easy grasp of the thickness distribution. In the prior art, since the thickness distribution has been grasped with reference to plural two-dimensional sectional views, plural two-dimensional sectional shapes must be designated. As a result, the procedures have been troublesome and the overall thickness distribution has not been able to be easily and quickly grasped.
It is an object of the present invention to provide a design system capable of designing an injection mold readily and in short time and a design method employed in the same.
According to the injection mold design system of the present invention, in case the product shape or the mold profile should be corrected, since lines or planes being obstructive to profile correction can be unloaded to a storing means temporarily, the designer may correct the product shape or the mold profile while monitoring the display screen on which only lines or planes indispensable to the certain profile correction are depicted. Therefore, with displaying a stereoscopic drawing and a-projection drawing of the product on the display device, the designer may execute correction of shrinkage rate, extraction of parting line, provision of draft slope, etc. in an interactive manner.
According to the injection mold design method of the present invention, design items can be reduced by preparing parameters of the mold parts and fixing parts as patternized information, and in addition correction, change, etc. of the product shape and the mold profile can be effected automatically. Consequently, man-hour of design in typical design operations can be significantly reduced.
According to the injection mold design method of the present invention, features of the mold which being indispensable to formation of the mold can be grasped by extracting candidates of split borderlines of the mold. In addition, lack of knowledge and experience as to the mold design can be made up for by utilizing a loop check function for the split borderlines and a nest split function. Thus, the design method of the present invention enables the designer having little experience to execute the mold design.
With the above, the present invention may extremely contribute to the mold design support system capable of executing correction of the product shape, design of the mold, and design of manufacturing jigs in an interactive manner.
The present invention has been made in light of such problems and it is an object of the present invention to provide a computer aided design system which is capable of performing more smoothly moldings design, mold design, or moldings fabrication by grasping design contents of the moldings more easily and more quickly to thereby shorten the time limit of delivery of the moldings, and a three-dimensional design method using the same, and a storing medium.
It is another object of the present invention to provide a computer aided design system which is capable of performing more smoothly moldings design, mold design, or moldings fabrication by carrying on information transfer more smoothly to thereby shorten the time limit of delivery of the moldings, and a three-dimensional design method using the same, and a storing medium.
More particularly, the present invention can provide a computer aided design system which is capable of performing more smoothly moldings design, mold design, or moldings fabrication by adding attribute information other than the above to the three-dimensional shape and thus by either grasping design contents of the moldings more easily and more quickly or carrying on information transfer more smoothly to thereby shorten the time limit of delivery of the moldings, and a three-dimensional design method using the same, and a storing medium.
There is provided a three-dimensional design method which is able to generate three-dimensional drawings in which attribute information are added to three-dimensional shape data of a synthetic resin moldings by use of a computer aided design system and then display images of the three-dimensional drawings on a screen,
the method comprising:
calculating a thickness distribution of the synthetic resin moldings based on the three-dimensional shape data by the computer aided design system; and
adding information indicating calculated thickness distribution to corresponding parts of the images of the synthetic resin moldings which is being three-dimensionally displayed as attribute information by the computer aided design system.
According to the three-dimensional design method, the advantage such that the mold design can be carried out more smoothly can be achieved since the thickness distribution can be grasped easily and quickly in the mold design. Still more, the advantage such that the thickness distribution can be confirmed easily and quickly to enable smooth manufacture of the moldings can be achieved when conditions such as temperature, pressure, etc. of melted molding material are to be decided in the plastics manufacturer.
The step of calculating the thickness distribution comprises,
deciding an opposing plane facing to a selected plane of the three-dimensional shape positioned on a thickness side according to whether a number of intersection points between a line segment of a normal which is positioned on one side of the selected plane and planes of the three-dimensional shape is even number or odd number, the normal being set orthogonally against the selected-plane, and
calculating a distance between the selected plane and the opposing plane positioned on the thickness side as a thickness.
According to the three-dimensional design method, the advantage such that the thickness distribution of any three-dimensional shape can be calculated automatically without fail can be achieved.
There is provided a three-dimensional design method which is able to generate three-dimensional drawings in which attribute information are added to three-dimensional shape data of a synthetic resin moldings by use of a computer aided design system and then display images of the three-dimensional drawings on a screen,
the method comprising:
designating type of print, shape, and print position on the three-dimensional shape for the computer aided design system as the attribute information; and
displaying images of the three-dimensional shape to be printed on the screen of the computer aided design system based on such designation.
According to the three-dimensional design method, the print contents can be grasped easily and quickly by confirming the mark MK in the plastics manufacturer, so that the print process can be carried out more smoothly.
There is provided a three-dimensional design method which is able to generate three-dimensional drawings in which attribute information are added to three-dimensional shape data of a synthetic resin moldings by use of a computer aided design system and then displaying images of the three-dimensional drawings on a screen,
the method comprising:
designating type of grains, and planes of the three-dimensional shape on which the grains are to be formed for the computer aided design system as the attribute information; and
displaying images of the three-dimensional shape to a designated plane of which grain information are added on the screen of the computer aided design system based on such designation.
According to the three-dimensional design method, the contents of grain addition can be grasped easily and quickly by confirming the above in the mold manufacturer and the plastics manufacturer, which makes it possible to decide the conditions of the mold design and the moldings manufacture more smoothly.
There is provided a three-dimensional design method which is able to generate three-dimensional drawings in which attribute information are added to three-dimensional shape data of a synthetic resin moldings by use of a computer aided design system and then displaying images of the three-dimensional drawings on a screen,
the method comprising:
designating planes of the three-dimensional shape as parting line disable planes of a split mold used for injection molding of the moldings for the computer aided design system as the attribute information; and
excepting selected split planes which intersect with the parting line disable planes if candidates of split planes of the split mold are selected in the computer aided design system.
According to the three-dimensional design method, the advantage such that the mold design can be carried out in response to the request of the moldings designer without fail can be achieved since information of the parting line disable plane can be transmitted precisely and firmly from the moldings design to the mold design.
There is provided a three-dimensional design method which is able to generate three-dimensional drawings in which attribute information are added to three-dimensional shape data of a synthetic resin moldings by use of a computer aided design system and then displaying images of the three-dimensional drawings on a screen,
the method comprising:
executing design change with use of the computer aided design system; and
storing information of design change parts as the attribute information in the computer aided design system while taking correspondence between the information of the design change parts before and after design change, and then displaying three-dimensionally different parts between other of the information of the design change parts before and after design change and one of the information thereof simultaneously while discriminating the other of the information from one of the information on a basis of one of the information of the design change parts beforehand after design change according to the information of the design change parts.
According to the three-dimensional design method, the advantage can be achieved such that the relationship before and after design change can be grasped more easily and more quickly according to such display, so that it is possible to carry out the mold design more smoothly.
There is provided a three-dimensional design method which is able to generate three-dimensional drawings in which attribute information are added to three-dimensional shape data of a synthetic resin moldings by use of a computer aided design system and then displaying images of the three-dimensional drawings on a screen,
the method comprising:
designating dimensional parts of the three-dimensional shape for the computer aided design system as the attribute information at a stage of product design, and setting tolerances of the dimensional parts;
displaying dimensions of the dimensional parts and tolerances onto the three-dimensional shape by the computer aided design system at a stage of mold design, and setting objective values of the dimensions of the dimensional parts based on the dimensions and the tolerances; and
correcting the dimensions of the three-dimensional shape so as to coincide the dimensions with the objective values.
According to the three-dimensional design method, the advantage can be achieved such that data with the dimensional tolerances which have been set in the moldings design can be utilized smoothly and effectively in the mold design.
In claim 8, there is provided a computer aided design system for use in any one of methods set forth in claims 1 to 7.
There is provided a storing medium for use in storing a program to implement methods set forth in any one of claims 1 to 7.
Other objects and configurations of the present invention becomes evident from the following description with reference to the accompanying drawings.